1. Field of Invention
This invention relates to a floating structure from which drilling or production operations are carried out. It relates especially to a special horizontal bearing assembly for use with the riser pipes of a Vertically Moored Platform.
In recent years, there has been considerable attention attracted to the drilling and production of wells located in water. Wells may be drilled in the ocean floor from either fixed platforms in relatively shallow water or from floating structures or vessels in deeper water. The most common means of anchoring fixed platforms includes the driving or otherwise anchoring of long piles in the ocean floor. Such piles extend above the surface of the water and support a platform attached to the top of the piles. This works fairly well in shallow water, but as the water gets deeper, the problems of design and accompanying cost become prohibitive. In deeper water, it is common practice to drill from a floating structure.
In recent years, there has been some attention directed toward many different kinds of floating structures. One system receiving attention for mooring is the so-called Vertically Moored Platform. A Vertically Moored Platform may be defined as a marine buoyant structure for drilling wells and/or producing hydrocarbons therefrom and anchored by essentially parallel, vertical, and elongated members such as riser pipes. In the preferred form of a Vertically Moored Platform, the riser pipes are without slip joints and provide the only anchoring means for the Vertically Moored Platform. Such a platform is described in several patents, including U.S. Pat. No. 3,648,638, issued Mar. 14, 1972, Kenneth A. Blenkarn, inventor.
2. Prior Art
The invention of this application is an improvement over the Vertically Moored Platforms described in the prior art. Such patents on the Vertically Moored Platform do not describe nor claim the horizontal bearing described herein, which is very useful for transmitting horizontal force between the riser pipe and the jacket or leg of the Vertically Moored Platform through which the riser pipe extends vertically. There are, of course, numerous bearings described in the prior art and are commercially available. However, I know of none similar to that bearing claimed herein for use with a riser pipe anchoring a Vertically Moored Platform.